I found this in the following link comparing  prairie and rainforest.

The rainforest operates in much the same manner other than it does not have its reserves

of nutrients stored as soil organic matter. It does not need storage because the nutrients

(and carbon) are stored in living materials that cycle quickly. In the prairie most of the

biological activity occurs in the soil or near the soil surface. In the rain forest, most of

the biology is above the soil. Soil scientists have traditionally thought of rainforest soils 

Title: Oh Say Can You C (sdnotill.com)